v1.2.0 — Undo / Redo Button

New Features

• Undo / Redo button — new button.ha_config_git_sync_undo_last_change entity
• Uses git revert HEAD --no-edit for safe, standard undo
• Acts as a toggle: first press undoes, second press redoes
• Automatically pushes the revert commit
• Sends notification on success/failure

Documentation

• Updated README with undo/redo section and file watcher feature

Testing

• 6 new undo unit tests + 3 new undo integration tests (53 total, all passing)